Tachometer not working. E40D NOT in limp mode, NO OD light flashing/on. ???

[thehollywoodjoe]

So, the tachometer on my 94 just went out. The TECM is getting good readings, though, as I am lead to believe by the absence of limp mode and OD light being on. The truck still drives as it always has, but without any tachometer now.

Here's what I've checked into so far:

1. Tach sensor - Swapped with a spare. Both read between the 2-3k ohm range when tested.
2. Wiring - No chaffing. Followed it to the passenger side, then back to the drivers side. Intact.
3. TECM Relay - Swapped with 2 other relays - Not having signs of TECM non-power (i.e. limp mode).
4. Fuses - Under dash and engine bay distribution box - all fuses are good.

I have a wiring diagram that is telling me a WHT/PNK wire from the PCM goes to the tachometer...I'm wondering if there is a way to test the tachometer itself?

Also, I can't check for codes since I don't know where the CEL/SES light is. The truck isn't a 4X4, but the dash bezel has 4X4 stuff on it...wondering if the PO changed it, etc.

Anyhow, any suggestions on where to look next would be appreciated.

-Joe

 

[thehollywoodjoe]

I took the gauge cluster *almost* out and put it back it...too much work to get it out of there with an automatic transmission PRND21 cable and a non-tilt wheel. Plus I had other things to do today instead of working on that all day.

The good news. This seems to have fixed the problem. Tach is back. Must be either a chaffed wire to the gauge or loose connection back there.

 

[FORDF250HDXLT]

your getting closer.as your finding out,many of these things can't really be traced out online.all we can do is help you get pointed in the right direction,which you are.
to remove the cluster,look in once the bezel is off and you'll see two screws that hold the PRND21 indicator w/cable on.remove those and then that slides down and out.i can see the extra difficulty without a tilt wheel to actual remove the gauge cluster though,even then.hmmm.perhaps you have to actually loosen and drop the whole steering column down a bit for it to clear.that's not actually "too" bad lol.just look up under and you'll see the 4 large nuts straight down.loosen those right up and the whole works will drop down and then the cluster will clear.
it's extremely important you find and repair this poor connection.your multi thousand dollar trans depends on it,or failure can result eventually.don't give up.your getting close now!

tip;
while your in there,closely inspect the od off push button/indicator button wire.where it rubs up on the metal underside.go ahead and replace if needed,if just starting to chafe through without bare wires yet,tape it up and wire loom it.this will prevent a fuse from blowing and having the trans enter limp mode and cause for future tracing and repair as well.since you'll be right there anyway.a little preventive maintenance for ya.